IOLite: phase 1b trial of doublet/triplet combinations of dostarlimab with niraparib, carboplatin-paclitaxel, with or without bevacizumab in patients with advanced cancer

BACKGROUND

Doublet combination therapies targeting immune checkpoints have shown promising efficacy in patients with advanced solid tumors, but it is unknown if rational triplet combinations will be well tolerated and associated with improved antitumor activity. The objective of this trial was to determine the recommended phase 2 doses (RP2Ds) and to assess the safety and efficacy of the programmed cell death protein 1 (PD-1) inhibitor dostarlimab in combination with (1) the poly(ADP-ribose) polymerase inhibitor niraparib with or without vascular endothelial growth factor inhibitor bevacizumab or (2) carboplatin-paclitaxel chemotherapy with or without bevacizumab, in patients with advanced cancer.

METHODS

IOLite is a multicenter, open-label, multi-arm clinical trial. Patients with advanced solid tumors were enrolled. Patients received dostarlimab in combination with niraparib with or without bevacizumab or in combination with carboplatin-paclitaxel with or without bevacizumab until disease progression, unacceptable toxicity, or withdrawal from the study. Prespecified endpoints in all parts were to evaluate the dose-limiting toxicities (DLTs), RP2Ds, pharmacokinetics (PKs), and preliminary efficacy for each combination.

RESULTS

A total of 55 patients were enrolled; patients received dostarlimab and: (1) niraparib in part A (n=22); (2) carboplatin-paclitaxel in part B (n=14); (3) niraparib plus bevacizumab in part C (n=13); (4) carboplatin-paclitaxel plus bevacizumab in part D (n=6). The RP2Ds of all combinations were determined. All combinations were safe and tolerable, with no new safety signals observed. DLTs were reported in 2, 1, 2, and 0 patients, in parts A-D, respectively. Preliminary antitumor activity was observed, with confirmed Response Evaluation Criteria in Solid Tumors v1.1 complete/partial responses reported in 4 of 22 patients (18.2%), 6 of 14 patients (42.9%), 4 of 13 patients (30.8%), and 3 of 6 (50.0%) patients, in parts A-D, respectively. Disease control rates were 40.9%, 57.1%, 84.6%, and 83.3%, in parts A-D, respectively. Dostarlimab PK was unaffected by any combinations tested. Coadministration of bevacizumab showed no impact on niraparib PKs. The overall mean PD-1 receptor occupancy was 99.0%.

CONCLUSIONS

Dostarlimab was well tolerated in both doublet and triplet regimens tested, with promising antitumor activity observed with all combinations. We observed higher disease control rates in the triplet regimens than in doublet regimens.

TRIAL REGISTRATION NUMBER

NCT03307785.

IOLite: Multipart, phase 1b, dose-finding study of the PD-1 inhibitor dostarlimab in combination with the PARP inhibitor niraparib ± bevacizumab (bev), or with platinum-based chemotherapy ± bev for advanced cancer

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Background: Novel combinations of drugs may overcome resistance in patients (pts) with solid tumors who had progressed on standard therapy. Methods: IOLite (NCT03307785) is a multicenter, open label, multipart study to determine dosing and evaluate safety and efficacy of dostarlimab in combination with approved therapies in pts with advanced solid tumors. Pts were enrolled in each part based on tumor histology, prior treatment (tx) history, and physician preference. Primary endpoint is dose-limiting toxicities (DLTs) deemed as tx-related per investigator, and safety and tolerability of the combination. Tumor responses were assessed per RECIST v1.1. Results: Parts A-D (see Table) are fully enrolled. One complete response was reported in part B (endometrial); confirmed partial responses in part A (ovarian, small cell lung [SCLC], gastrointestinal stromal [GIST]); part B (breast [2], bladder, SCLC); part C (prostate, fallopian tube), and part D (endometrial, non-SCLC). Stable disease was reported in part A (colorectal, prostate [2], breast, GIST, gastric); part B (SCLC, squamous cell, head and neck, prostate); part C (pancreatic, ovarian, GIST, breast [2], liver, endometrial); part D (ovarian, head & neck, cholangiocarcinoma). At data cutoff, 24 pts remain on treatment. PK’s of dostarlimab and niraparib (nir) were not altered by any of the combination agents tested. Conclusions: Dostarlimab is well tolerated in combination with nir ± bev, or carbo-pac ± bev. Preliminary efficacy data show responses in various histologies. No new safety signals were identified. Clinical trial information: NCT03307785. [Table: see text]

The RAPID method for blood processing yields new insight in plasma concentrations and molecular forms of circulating gut peptides

The correct identification of circulating molecular forms and measurement of peptide levels in blood entails that the endocrine peptide being studied is stable and recovered in good yields during blood processing. However, it is not clear whether this is achieved in studies using standard blood processing. Therefore, we compared peptide concentration and form of 12 (125)I-labeled peptides using the standard procedure (EDTA-blood on ice) and a new method employing Reduced temperatures, Acidification, Protease inhibition, Isotopic exogenous controls, and Dilution (RAPID). During standard processing there was at least 80% loss for calcitonin-gene-related peptide and cholecystokinin-58 (CCK-58) and more than 35% loss for amylin, insulin, peptide YY forms (PYY((1-36)) and PYY((3-36))), and somatostatin-28. In contrast, the RAPID method significantly improved the recovery for 11 of 12 peptides (P < 0.05) and eliminated the breakdown of endocrine peptides occurring after standard processing as reflected in radically changed molecular forms for CCK-58, gastrin-releasing peptide, somatostatin-28, and ghrelin. For endogenous ghrelin, this led to an acyl/total ghrelin ratio of 1:5 instead of 1:19 by the standard method. These results show that the RAPID method enables accurate assessment of circulating gut peptide concentrations and forms such as CCK-58, acylated ghrelin, and somatostatin-28. Therefore, the RAPID method represents an efficacious means to detect circulating variations in peptide concentrations and form relevant to the understanding of physiological function of endocrine peptides.

The effect of pancreatic and biliary depletion on the in vivo pharmacokinetics of digoxin in pigs

Several transporter systems in the liver and intestine are known to change their expression and function during cholestatic disease states. The objective of the present in vivo study was to investigate the effect of biliary depletion, as a method to mimic cholestasis, on the bioavailability and disposition of digoxin in biliary and pancreatic duct cannulated pigs. The study was divided in two parts. In the first part, a solution of 10 microg/kg digoxin was administered intravenously to the cannulated pigs with intact enterohepatic circulation (Control) and during depletion of the bile and pancreatic juice. In the second part, the same dose of digoxin was administered intraduodenally with intact enterohepatic circulation (Control) and during depletion of either bile or pancreatic juice or both. Biliary depletion decreased the flow of bile and pancreas juice as well as the amount of digoxin appearing in the bile. Deprivation of both bile and pancreas juice significantly increased the bioavailability of digoxin, the plasma AUC after enteral administration increased from 17.6+/-4.2 nmol/lh (Control) to 29.6+/-8.3 nmol/lh (P<0.05). The biliary clearance decreased significantly, from 0.22+/-0.11 l/h/kg (Control) to 0.04+/-0.03 l/h/kg during pancreatic and biliary depletion (P<0.05). There was a significant decrease in elimination half-life (P<0.05) and volume of distribution (P<0.01) during the depletion experiments while the systemic clearance remained unchanged. The results clearly suggest that biliary depletion trigger a short-term downregulation, most likely posttranscriptionally mediated, of a sinusoidal uptake transporter in the liver, possibly a pig ortholog of OATP.

Sodium-iodide symporter mediates iodide secretion in rat gastric mucosa in vitro

In vivo studies on rats have demonstrated that considerable amounts of iodide are transported from the bloodstream into the gastric lumen. The mechanisms for and functional significance of this transport are poorly understood. Active (driven by Na(+)/K(+)-ATPase) iodide transport into thyroid follicular cells is mediated by the sodium-iodide symporter (NIS), which is also abundantly expressed in gastric mucosa. We aimed to further investigate the iodide transport in gastric mucosa and the possible role of NIS in this transport process. Iodide transport in rat gastric mucosa was studied in vitro in an Ussing chamber system using (125)I as a marker. The system allows measurements in both directions over a mucosal specimen. A considerable transport of iodide (from the serosal to the mucosal side) was established across the gastric mucosa, whereas in the opposite direction (mucosa to serosa), iodide transport was negligible. Sodium perchlorate (NaClO(4)), a competitive inhibitor of NIS, and ouabain, an inhibitor of the Na(+)/K(+)-ATPase, both attenuated gastric iodide transport from the serosal to the mucosal side. To investigate a possible neuroendocrine regulation of the iodide transport identified to occur from the serosal to the mucosal side of the stomach, thyroid-stimulating hormone (TSH), thyrotropin-releasing hormone (TRH), vasoactive intestinal peptide (VIP), histamine, or nitric oxide donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) was added. None of these substances influenced the iodide transport. We conclude that iodide is actively transported into the gastric lumen and that this transport is at least partly mediated by NIS. Additional investigations are needed to understand the regulation and significance of this transport.

Three-Day Enteral Exposure to a Red Kidney Bean Lectin Preparation Enhances the Pancreatic Response to CCK Stimulation in Suckling Pigs

BACKGROUND

A reason for the digestive problems that often occur around early weaning in piglets could be that the pancreas is not yet fully developed and the enzymes required for degradation of the solid food are not secreted in enough amounts.

OBJECTIVES

The aim of the study was to investigate the possibility of inducing pancreas maturation with enhanced enzyme secretion.

METHODS

10-day-old suckling pigs were gavage fed with a red kidney bean lectin preparation for 3 days, and the pancreatic response to intravenous infusion of CCK-33 was measured in the anaesthetized animals fitted with pancreatic duct catheters.

RESULTS

The pancreatic fluid secretion, protein output, and the trypsin and amylase outputs were significantly increased in response to CCK stimulation after the lectin treatment, as compared to those of the control littermates (p < or = 0.05). In addition, the plasma insulin basal levels and those observed during CCK-33 stimulation were lower in the lectin-treated piglets.

CONCLUSION

The results suggested that the lectin treatment led to an increase in the capacity for pancreatic enzyme secretion in the suckling piglets. An enhanced pancreatic function might help to ameliorate the problems that may appear in modern pig production which are associated with weaning.

CCK-B receptor antagonist YF476 inhibits pancreatic enzyme secretion at a duodenal level in pigs

BACKGROUND

To evaluate the mechanisms by which cholecystokinin (CCK) regulates the exocrine pancreas, the role and location of CCK receptors in the pig were investigated using the CCK-B receptor antagonist YF476 and different administration routes of CCK.

METHODS

In 11 anaesthetized pigs, catheters were surgically implanted in the pancreatic duct for juice collection, and in the gastric arteries and jugular vein, so that infusions of CCK-33 could be directed to the duodenal/gastric, duodenal/pancreatic or general circulations, respectively. Experiments were performed under control conditions, and after pretreatment by gavage feeding with YF476, using either a single, low dose of 0.3 micromol kg, which would block the CCK-B receptors, or a 1000 times higher dose (300 micromol kg), which would also block the CCK-A receptors.

RESULTS

The increase in the pancreatic output of protein and the enzymes trypsin and amylase observed after the infusion of CCK-33 at 13 pmol kg to the duodenum/stomach or duodenum/pancreas was inhibited by pretreatment with YF476 at both dosages. In contrast, the increase in protein and enzyme output after the infusion of a supraphysiological dose of CCK-33 (130 pmol kg) to the general circulation was not affected by pretreatment with low dosage YF476, whereas high dosage YF476 completely inhibited the stimulated secretion.

CONCLUSIONS

These data indicate that CCK-33 given locally to the duodenum in doses raising CCK to physiological plasma levels stimulates the pancreatic enzyme secretion via duodenal CCK-B receptors. Supra-physiological doses of CCK-33 to the general circulation appeared to affect the pancreatic enzyme secretion via CCK-A receptors located elsewhere than in the pancreatic and duodenal tissue.

CCK regulates pancreatic enzyme secretion via short duodenal-pancreatic reflexes in pigs

BACKGROUND

Different routes of administration of CCK-33 and blockage of CCK-A and muscarinic (m3) receptors are used in this study to evaluate the mechanisms by which cholecystokinin can stimulate the exocrine pancreas.

METHODS

The experiment was performed on eight anaesthetized pigs during control conditions and after administration of the CCK-A and m3 receptor antagonists, Tarazepide and 4-DAMP, respectively. Catheters were surgically implanted in the pancreatic duct for juice collection and in the gastric and right gastro-epipoic arteries and in the jugular vein, so that infusions of CCK-33 could be made exclusively to the duodenum/stomach, duodenum/pancreas or general circulation, respectively.

RESULTS

Infusion of a low dose of CCK-33 (13 pmol kg(-1)) to the general circulation did not affect pancreatic protein or trypsin output. When the same dose was given directly to the duodenum/stomach or the duodenum/pancreas, pancreatic output increased during both control conditions and after Tarazepide and/or 4-DAMP treatment, though the increase in trypsin output was lower after Tarazepide and/or 4-DAMP blockade. A high dose of CCK-33 (130 pmol kg(-1)) given peripherally stimulated the pancreatic secretion, but this response was totally abolished in Tarazepide and 4-Damp treated animals.

CONCLUSIONS

Pancreatic enzyme secretion due to CCK-33 stimulation depends on the presence of short duodenal-pancreatic peptidergic reflexes evoked mainly via low sensitive, probably CCK-B, receptors located in the duodenum/stomach. Pancreatic secretion evoked by peripheral CCK-33 in pharmacological doses was independent of m3 receptors blockade but depended on CCK-A receptors located elsewhere than in the duodenum/pancreas.

Influence of intraduodenally infused olive and coconut oil on postprandial exocrine pancreatic secretions of growing pigs

The effect of dietary vegetable oils differing in fatty acid composition that were infused directly into the duodenum on exocrine pancreatic secretions in pigs has not previously been studied. The objective of the present study was to determine the acute response of the exocrine pancreas to vegetable oils with various fatty acid profiles under prandial conditions. Six growing pigs (BW 13.2 kg) were surgically prepared with pancreatic duct catheters and duodenal reentrant T-cannulas. The animals were fed twice a day (1000 and 1600) a commercial weaner diet at a rate of 2% of BW. Beginning with the morning feeding, olive oil, coconut oil, or saline as a control were infused in boluses every 5 min in total 0.1% of BW over a period of 1 h directly into the duodenum according to a 3 x 3 Latin square design. Pancreatic juice was collected over a period of 4 h, beginning 1 h preprandially (0900) until 3 h postprandially (1300). A time effect was observed after the infusion of olive oil on the volume of secretion, on protein contents and outputs, as well as on lipase contents and outputs and on colipase contents. The infusion of saline and coconut oil changed the runs of the curves for lipase and colipase outputs. No time x treatment interactions were observed regarding volume of secretion, protein contents and outputs, trypsin contents and outputs, and lipase outputs. The runs of the curves for lipase contents were different between the olive oil and saline treatment and between the olive oil and coconut oil treatment. The runs of the curves for the olive oil and saline treatment differed from each other regarding colipase contents. Pooled values of colipase outputs were elevated after coconut oil treatment, and a positive correlation between trypsin and colipase contents was found. Under prandial conditions, the exocrine pancreas responds differently in its acute secretion to different vegetable oils due to the differences in the fatty acid profiles.